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Irlam 24i16 (top)
Irlam 24i16 (back)
Irlam 24i16 (bottom)
Note that this Irlam 24i16 has 4 V-DRAM chips in the locations marked Bank A Lower/Upper and Bank B Lower/Upper. The Video DRAM chips are NEC D482234s which are Mbit x1 so there is a total of 1MB Video DRAM.
Irlam 24i16 (top)
This Irlam 24i16 came from a Risc PC used at Acorn for the developement of the Set Top Box 1.
Irlam 24i16 (back)
Irlam 24i16 (bottom)
Note that this Irlam 24i16 only has V-DRAM chips in the Bank A locations, Bank B is not fitted. This card has 512KB Video DRAM.
The Irlam Instruments 24i16 is a 24 Bit Real-Time Video Digitiser & 16 Bit Sound Sampler. The following description is taken from the Irlam Instruments web site [deceased].
Irlam Instruments has had considerable experience with high performance video digitisers and16 bit sound samplers for RISC OS machines. 24i16 is the latest expansion card to benefitfrom this work by combining a real-time 24 bit video digitiser with a very high quality 16 bitaudio capture and playback system. This makes it suitable for many of todays educational, business and home applications where high quality stills, samples and movies are required.
24i16 is unique in that it is the first (and only) digitiser which can:
Video is accepted from any composite or S-Video source including Video Recorders, Camcorders, Video Cameras, VideoDisc players and Still Video Cameras.
The standard digitiser allows a full television field to be captured in real-time(20 milliseconds). This can be extended to allow still images to be obtained up to fullTV frame size, which is useful for capturing really impressive stills fromcameras such as Sony Mavica, Canon ION RC-560 or Video Visualizer.
Built-in scaling hardware allows image sizes smaller than fields or frames to be captured. Filtering circuits anti-alias the scaled images in two-dimensions so that smooth images are produced. Moving sequences can be saved direct to disc at up to 25 images per second (ips). Note that image size and rate of capture is limited only by disc and system bandwidths, whichmeans that movies can be obtained at a wide range of sizes, rates and aspect ratios.
24i16 boasts a 16 bit stereo sound sampler which records (and plays back) at Compact Disc and Digital Audio Tape frequencies. Samples are recorded direct-to-disc giving virtually unlimited duration. A special resource allows the audio tracks from Replay movies to be played through the 16 bit output of 24i16 which dramatically improves their audio quality. Raw audio from the Acorn sound system can be filtered and mixed in with the 16 bit output to give improved sound quality.
A sophisticated RISC OS application supplied allows 24i16's features to be accessed quickly and easily. Image size, capture rate, audio sampling frequency and file format can all be controlled from the desktop. Video is monitored on-screen (and displayed in true colour on 16/32 bit desktops). Contrast, brightness, saturation and hue are software adjustable. Audio may be monitored using an oscilloscope display and/or VU meters. You can also hear the audio using the 16 bit output from 24i16 or via the speaker of your A5000, RISC PC etc.
The recording process works just like a cassette recorder; connect the audio/video source and press the record button, then press stop when you have captured the desired amount (or set a pre-defined duration). You can even perform time-lapse capture so that movies can be made of flowers opening or clouds forming etc. Documentation supplied includes details and examples of how to operate 24i16 simply from your own software written in BASIC, C or Assembler.
The features of the video system:
The application can export and record:
Video can come from any composite PAL or S-Video (separate brightness and colour signals)source. Inputs are 75 ohm terminated.
Decoding is carried out in the digital domain by a multi-standard device which also acceptsNTSC and SECAM standards. PAL video is square-pixel sampled at 14.75 MHz giving 768 activepixels per line.
A 1 MByte VRAM framestore is supplied as standard. The VRAM controller is unusual inthat it packs lines of video contiguously into memory so that a full PAL field of 768 pixelsby 288 or 576 lines can be stored. Fields and frames are captured in real-time i.e 20 and 40milliseconds respectively.
Moving sequences can be captured at up to 25 images per second (ips). The image sizeand rate is limited only by the disc and system bandwidths. On a typical system you canobtain movies 152 by 108 in colour at 25 ips and 208 by 134 in colour at 12.5 ips. Theseare examples only - there are many other combinations that you can achieve.
Images are stored with 8 bits of brightness (luminance) and 8 bits of each colourdifference signal (U & V) giving a 24 bit range. The luminance and chrominancesignals are sampled in a standard 4:2:2 ratio.
A large amount of effort has been expended to ensure that reading video & audio dataacross the expansion bus is as fast as possible. Fast MEMC cycles are used (over 99% ofwhich complete without wait-states) and reading is allowed to proceed even whilstcapturing is in progress.
An expansion port is fitted as standard to 24i16 which provides easy access to thescaled video data. This is to allow connection to future Irlam and third party products.
Stereo Line and Mic (+20dB selectable gain) inputs on phono connectors. 16 bit Stereo3.5mm line output.
Variable input gain and line output volume.
Stereo and mono file formats supported.
Integrates with existing Acorn sound system so output from the built in sound system canbe sampled and the 16 bit & VIDC outputs can be mixed together.
Audio can be sampled in 16 bit or 8 bit modes (including linear and 8 bit log for VIDC).
Built-in hardware ADPCM compression which gives high quality 16 bit sound at 4:1 compression ratio.
Samples are saved in Replay, Armadeus, VOC and industry standard Wave file format.
A wide range of sampling rates is supported including; 5.51, 6.62, 8.0, 9.6, 11.025, 16.0,18.9, 22.05, 27.42, 32.0, 33.075, 37.8, 44.1 & 48.0 KHz.
Here is the Irlam Instruments 24i16 Multimedia System manual.
Here is a archive of the 3 Irlam Instruments 24i16 Application discs .